Switch apparatus for detecting delivery of parts



G. WINTRISS Feb. 27, 1962 SWITCH APPARATUS FOR DETECTING DELIVERY OFPARTS Filed Nov. 20. 1959 m 6 H M w o 4 Ra m 4 6 m I oo To PRESS STOPCIRCUIT INVENTOR.

' ATTORNEYS United States Patent Office 3,023,283 Patented Feb. 27, 19623,023,233 SWITQH APLARATUS FOR DETEQTENG DELIVERY OF RQRTS GeorgeWintriss, Carversville, Pa. Filed Nov. 20, 1959, Ser. No. 854,296 11Claims. ((11. Nth-61.41)

This invention relates to control apparatus for protecting machines andmore especially machines having punches and dies, or similar elements,for making parts. More particularly, the invention is concerned withsystems for stopping further operation of a machine if a part is notdelivered at the time when it should be. By detecting such missingparts, the invention is made responsive to irregularities in theoperation of the machine regardless of where the trouble may exist. Forexample, the invention will be responsive to a failure of an automaticfeed as well as to jamming of a part in a die, since the failure of themachine to deliver a part at the proper time in the cycle is a definiteindication of improper operation of some part of the system.

It is an object of the invention to provide an improved safety controlfor machines, and with the safety control responsive to the operation ofa missing-part detector. The invention includes a control system inwhich the operation of the missing-part detector is coordinated with theoperation of the elements of the machine so that the missing-partdetector is conditioned again for every cycle of operation of themachine.

Another object of the invention is to provide an improved detector inthe path of delivery of work pieces from a machine, and with feelersconstructed and spaced so that parts delivered from the machine willoperate one or more of the feelers, even though the parts are small andmovable along courses which vary considerably from one side to the otherof a conveyor, delivery chute, or other discharge means on the deliveryside of the machine.

Other objects, features and advantages of the invention will appear orbe pointed out as the description proceeds.

In the drawing, forming a part hereof, in which like referencecharacters indicate corresponding parts in all the views:

FIGURE 1 is a diagrammatic view of a missing-parts detector system, madein accordance with this inven tion, and connected with elements of amachine which is to be protected;

FIGURE 2 is a greatly enlarged, front view of the missing-parts detectorshown in FIGURE 1;

FIGURES 3 and 4 are enlarged sectional views taken on the lines 33 and4-4, respectively, of FIGURE 2;

In FIGURE 1, a punch press is is shown diagrammatically. This pressincludes a ram 12 which moves up and down in a bearing 14 and which haspunches E6 in position to operate on a strip 18 carried by a die 24).Parts punched from the strip 18, and stripped in the usual way, areblown into a delivery chute 24 by compressed air from blast nozzles 26.

The delivery chute 24 has a bottom 27 and side walls 28. At thedischarge end of the delivery chute 24, there is a bracket 30 attachedto the upper portions of the sides 28. This bracket 30 supports amissing-part detector 32 having feelers 34 extending downwardly to thebottom 27 of the delivery chute.

In the construction shown, the feelers 34 are located at the end edge ofthe bottom 27 and they extend slightly below the top surface of thechute bottom 27.

The feelers 34 are pivotally supported at their upper ends so that theyare free to swing outwardly away from the end of the delivery chute; andthey do swing outwardly when struck by a part 36 as the part is blowndown the delivery chute 24 by compressed air from the blast nozzles 26.

The number of feelers 34 which are displaced by the part 36 depends uponthe transverse dimension of the part at the particular orientation whichthe part may have at the time it strikes the feelers 34. The spacing ofthe feelers 34 from one another is less than the minimum width of anypart which may be delivered from the machine which the invention isdesigned to protect.

The missing-part detector 32 will operate with parts traveling along thechute bottom 27, and equally well with parts blown through the air outof contact with the bottom or other surfaces of a delivery chute. Themiss ing-part detector will also operate in co-operation with a conveyorbelt and the feelers 34- may be at the end of the belt or they may bedisposed above the belt with their lower ends hanging down close to theconveyor surface along which the parts travel, and in any event, at adistance from the conveyor surface less than the height of the partswhich move the feelers when the machine is operating satisfactorily andparts are being delivered in accordance with the time cycle of themachine.

There is a switch 40 responsive to the movement of the punches 16 withrespect to the stationary die 2'3. This switch includes a movablecontact 42 attached to the ram 12 by a bracket 44; and includes also arelatively fixed contact 46 held in a bracket 48 attached rigidly to afixed part of the frame of the machine. Thus, the contact 46 is in afixed relation to the die 2%.

The contacts 42 and 46 are adjusted so that they touch one another whenthe machine is operating during the part of its cycle when a from thedelivery chute 24.

In order to allow for reasonable variations in the operation, the switch49 remains closed for a period starting some time before a part shouldreach the discharge end of the delivery chute and extending for sometime after the part should be discharged from the chute.

The switch 4% is grounded on the machine and is connected at its otherside, by a conductor 50, to a controller 52. The missing-part detector32 is connected with the controller 52 by a conductor 54-.

The controller 52 has terminals 56 with conductors leading to a circuitthat stops the operation of the machine. With punch presses, the circuitfrom the terminals 56 operates the clutch so as to prevent theapplication of power from the flywheel to the ram 12 for the next cycleof the machine if the controller has not received an impulse from thedetector 32 during the time that the switch 49 was closed during anysuccessive cycle.

A reset switch 60 is connected with terminals 62 of the controller foroperating the machine during times when no delivery of parts can beexpected; as when initially threading a strip of stock into the machine.

FIGURES 24 show the construction of the missingparts detector. Each ofthe feelers 34 is made of spring material and has a curved upper endwhich fits around an axle 66 extending for the full transverse width ofthe detector. This axle 66 is supported by a block 6% which ispreferably made of hard plastic, or some other electrical insulatingmaterial. There are slots 72 in the top of the block 68 for exposing theportions of the axle 66 around which the upper ends of the individualfeelers 34 extend. The portions of the block. 68 between the slots 72provide spacers 76 for holding the upper ends of the feelers 34 at thedesired spacing from one another.

The flat sides of the spring material, of which the feelers 34 are made,extend around the axle 66; but at locations near the bottom of the block68 there is a twist 78 in each of the feelers 34 so that the lowerportions of the feelers have their narrow edges confronting thedelivered parts which strike the feelers. This disposes the feelers 34in positions having the greatest part 36 should be discharged amazesstrength for resisting bending as a result of the repeated blows ofparts striking the detector.

In order to hold the feelers 34 in parallel relation, there are studs 82extending from the face of the block 68, there being one stud 82 betweenevery feeler 34 and its next adjacent feeler. These studs 32 are ofsubstantially the same width as the spacing between the feelers 34; andthey have tapered ends for guiding the feelers back into proper positionas a fceler swings downwardly toward the block 68 after eachdisplacement of the fecler. ln the construction illustrated, the feelers34 are of zigzag shape below the twists 78 so as to eliminate thepossibility of a flat and narrow part being blown between successivefeelers. With larger parts having no narrow dimension, straight feelersare just as effective as those shown in the drawing.

There is a spring 86 stretched across the full transverse width of thedetector at the upper end of the block 68 and outside of the curvedupper ends of the feelers Each of the feelers 34 moves into contact withthe spring 86 when the feeler 34- swings outward, as shown in dottedlines in FTGURE 4-.

The axie 66 is connected with one side of a circuit, and the spring 86is connected with the other side of the circuit. The feelers 34,therefore, serve as switches for closing a circuit between the axle 66and the spring 86 whenever the feelers 3d swing into contact with thespring 36. Either the axle 66 or the spring 36 can be connected to theconductor 54 of FIGURE 1. The other side of the detector is grounded.

Since the feelers 34 are of light weight, it is desirable to providemeans for holding them in a vertical direction when they are notdisplaced by the delivery of a part from the machine. This isparticularly true with installations where the parts are propelledtoward the detector by a blast of compressed air. Without some means forholding the feelers in their downwardly hanging position, the blast: ofair could displace the feelers in a manner similar to the effect of apart delivered from the chute.

In the construction illustrated, the feelers 34 are held in theirdownwardly hanging positions by magnets 92 located in sockets 94 in thefront face of the block 68. The magnets are relatively loose in thesockets 94 so that no accurate facing of the magnets and the insulatingblock 68 is required. Each magnet 92 is held in its socket 94 by a pin96 extending through the block 68 above and below the magnet. There is avertical groove 98 in the front face of each magnet 92 providingclearance for the pin 96.

The faces of the magnets 92 are preferably flush with the face of theblock 68; but the pins 1% are located so as normally to leave someclearance for the magnets 92 to move outwardly into contact with thefeelers 34 in the event that any feeler 34 touches the face of the block68 before coming in contact with its magnet 92.

In the illustrated construction, there are two rows of magnets 92, withthe magnets in the respective rows located in staggered relation to oneanother. This provides two magnets for holding each of the feelers 34.The diameter of each magnet is substantially equal to, or slightlygreater than, the transverse width of two feelers 34 and the spacebetween the feelers, as shown clearly in FIGURE 2.

The wiring of the detector can be modified so as to connect the magnetat one side of the detector circuit, and the magnet at the other end ofthe detector to the other side of the circuit. When so connected, thefeelers 34, in contact with all of the magnets, provide a series circuitfrom one end magnet to the other, and the movement of any feeler out ofcontact with its magnet will break the circuit to provide an impulse forthe controller.

It will be understood that the operation of the controller can becontrolled by either making or breaking a circuit, since the breaking ofa circuit can supply current when necessary through the de-energizing ofa relay which closes another circuit when tie-energized.

The invention has been described in connection with a delivery chutewhich is to be considered representative of conveyors, and the termconveyor is used herein to indicate any apparatus, either fixed ormoving, along which a part is delivered from a machine. The preferredembodiment of the invention has been illustrated with multiple feelers34, but it will be understood that a single fceler is sufficient forinstallations where the parts delivered are large, or always travelalong an identical path as they come from the machine.

Various changes and modifications can be made in the illustratedconstruction without departing from the invention as defined in theclaims.

What is claimed is:

l. in a machine having a work station where an operation is performed ona work piece, an operation-performing element having relative movementtoward and from the work piece at said work station, means fordislodging a work piece from the work station along a discharge pathafter each cycle of operation of the machine, first electric circuitmake-and-break means that move in timed relation with said relativemovement of the operationperforming element between a controlling andnon-controlling position, a missing-parts detector located along saiddischarge path and including second electric circuit make-and-breakmeans with a movable feeler extending into position to be struck by apart discharged along said path, and a controller that stops theoperation-performin g element when the feeler of the second electriccircuit make-and-break means remains undisturbed while the firstelectric circuit made-and-brcak means is in said controlling position.

2. The combination described in claim 1 and in which there is a deliverychute along which successive parts are delivered from the machine andsaid chute constitutes the discharge path, and the missing-partsdetector includes a plurality of feelers hanging down across the crosssection of the chute and closely spaced from one another transversely ofthe chute.

3. The combination described in claim 2 and in which the lower portionsof the feelers are of zig-zag contour in directions to increase theeffective width of the feelers transversely of the chute.

4. The combination described in claim 2 and in which the end portions ofthe feelers constitute movable contacts of the second electric circuitmake-and-break means.

5. The combination described in claim 4 and in which all of the portionsof the feelers that are movable contacts 0f the second electric circuitmake-and-break means are in parallel with one another,

6. The combination described in claim 2 and in which there are magnetsin position to hold each of the feelers in its downwardly hangingposition.

7. The combination with a machine having relatively movable elements,one of which operates through a cycle to make a part, of a firstelectric circuit make-and-break means having contacts that move towardand from one another in timed relation with movement of one of saidelements, a missing-parts detector located in the path of movement ofparts delivered from the machine, the missing-parts detector includingsecond electric circuit makeand-break means and an operator for thesecond electric circuit rnake-and-break means consisting of a movablefeeler extending into position to be struck by a part delivered from themachine, and a controller for the machine in the circuit with both thefirst and second electric circuit make-and-break means, and in whichthere is a delivery chute along which successive parts are deliveredfrom the machine, and the missing-parts detector includes a plurality offeelers hanging down across the cross section of the chute and closelyspaced from one another transversely of the chute, and there are magnetsin position to hold each of the feelers in its downward-ly-hangingposition, and there is a block with a downwardly-extending face acrosswhich the feelers extend when in their downwardly-hanging positions, andthe magnets for holding the feelers are mounted in sockets in the blockand are loose in the sockets so as to provide accommodation of themagnets to the positions of the feelers across the locations where thesockets open through the downwardly-extending face of the block.

8. The combination described in claim 7 and in which there is a pinextending across a recess in the face of each of the magnets forpreventing the magnets from coming out of the sockets in the block.

9. The combination described in claim 7 and in which there are two rowsof magnets in staggered relation to one another and the magnets are ofsuch widths that each of the feelers crosses the face of a portion ofone magnet of an upper row and a portion of another magnet of the lowerrow.

10. The combination with a machine having relatively movable elements,one of which operates through a cycle to make a part, of a firstelectric circuit make-and-break means having contacts that move towardand from one another in timed relation with movement of one of saidelements, a missing-parts detector located in the path of movement ofparts delivered from the machine, the missing-parts detector includingsecond electric circuit makeand-break means and an operator thereforconsisting of a movable feeler extending into position to be struck by apart delivered from the machine, and a controller for the machine in thecircuit with both the first and second electric circuit make-and-breakmeans, and in which there is a delivery chute along which successiveparts are delivered from the machine, and the missing-parts detectorincludes a plurality of feelers hanging down across the cross section ofthe chute and closely spaced from one another transversely of the chute,and there are magnets in position to hold each of the feelers in itsdownwardly-hanging position, and each of the feelers is made of flatspring material and the wide face of the feeler is transverse of thedirection of movement and extends downwardly from the upper end thereoffor a substantial distance, and each feeler has a twist in a positionintermediate the upper and lower ends positioning the lower portions ofthe feelers, with which the parts contact, with narrow edges toward thedirection from which the parts are projected against the feelers.

11. A missing-parts detector for location in the paths of movement ofparts delivered from a machine, the detector including electric circuitmake-and-break means having a plurality of feelers extending downwardlyand across the paths of movement along which parts are delivered fromthe machine, and a make-and-break circuit controlled by said electriccircuit make-and-break means and responsive to the displacement of oneor more of the feelers by a part passing along said path, and in whichthe feelers extend downwardly across a face of a support, and there aremagnets located in sockets in said face of the support in position tohold the feelers in their downwardly-extending positions in spite of airblasts delivered along the path which is to be followed by the parts.

References Cited in the file of this patent UNITED STATES PATENTS701,248 Bannon May 27, 1902 1,118,283 Holdefer Nov. 24, 1914 2,338,002Mero Dec. 28, 1943 2,615,081 Hoff Oct. 21, 1952 2,671,148 SchulenburgMar. 2, 1954 2,743,925 Elliott et al May 1, 1956

